How did this Shah get to achieve his lofty position?
US and British sponsored coup, I think.
From Wikipedia:
In 1953 the Iran's constitutionally and democratically elected nationalist prime minister, Dr. Mohammed Mossadegh had nationalized the oil industry, much to the anger of the United States and Great Britain. This resulted in an embargo on Iranian oil exports, which only worsened the already fragile economy. To gain control over the Iranien oil industry the CIA funded and lead a coup to overthrow prime minister Mohammed Mossadegh (see Operation Ajax). The coup initially failed and Mohammad Reza had to flee Iran. After a brief exile in Italy the Shah was brought back again through, this time a succesful, second coup. Mossadegh was arrested, tried and put in house arrest. General Fazlollah Zahedi had been handpicked to succeed prime minister Mohammed Mossadegh.
The CIA put him in place. This is when the CIA was an agency in support of the United States as opposed to the CIA of today which is so full of Clintonistas that it is an enemy of the United States.
My relatives engineered a coup to overthrow the then communist dictator of Iran.